弱胶结巷道围岩全断面锚固支护时机-支护参数综合影响分析

    Analysis of the comprehensive influence of support timing and support parameters on the full section anchors of weakly cemented roadway surrounding rock

    • 摘要: 针对我国西部某矿区绿色矿山建设过程中巷道出现的锚杆失效、顶板垮落等问题,基于应力释放理论和FLAC3D数值模拟软件建立了全断面锚固力学模型,与理论解进行对比验证了模型的可靠性。分析了巷道开挖后围岩应力释放过程中塑性区、应力场和位移场的演化规律;探讨了锚杆支护时机对围岩位移控制和锚杆轴力的影响,指出锚杆最佳支护时间;基于锚杆最佳支护时间讨论了锚固密度、锚固长度和锚杆预紧力对围岩位移控制的影响。研究结果表明:巷道开挖后,围岩产生过大的塑性变形是导致巷道破坏的主要原因,对巷道进行锚杆支护时主要控制围岩塑性变形;支护时机对锚固-围岩系统有显著影响,过早支护会导致锚杆轴力过大,增加锚杆破断风险;过晚支护则会导致巷道发生较大变形,影响巷道稳定性。巷道最佳支护时间为围岩应力释放率达到0.80~0.85之间。支护参数优化:提高锚杆支护密度、增大锚杆预紧力对围岩控制效果显著,而增加锚杆长度对围岩位移的约束效果并不明显。因此,对巷道进行锚杆支护时应在确定合理的支护时间的情况下选择短锚杆、高密度和高预紧力的支护方案,确保巷道稳定性和安全性。

       

      Abstract: In response to the problems of anchors failure and roof collapse encountered during the construction of a green mine in a mining area in Western China, a full section anchoring mechanical model and numerical model of the roadway are developed. This model grounded in stress release theory and utilizing FLAC3D software. The accuracy of the numerical model is validated through comparison with theoretical solutions. The paper analyzes the evolution of the plastic zone, stress field, and displacement field within the surrounding rock following roadway excavation. It explored how the timing of anchors installation influences the control of surrounding rock displacement and the axial force on the anchors, pinpointing the optimal timing for anchors support. Additionally, the impact of anchor density, anchor length, and pre-tension on the control of surrounding rock displacement is examined, all based on the established optimal support timing for the anchors. This research results indicate that excessive plastic deformation of the surrounding rock after roadway excavation is a principal cause of roadway failure. Therefore, the main objective of anchors support in roadways is to control the plastic deformation. The support timing significantly affects the performance of the anchors-surrounding rock system: early support will lead to excessive axial forces on the anchors, increasing the risk of breakage. Conversely, delayed support results in considerable deformation of the roadway, compromising its stability. In summary, the optimal support timing for the roadway, as determined by this study, is when the stress release rate with the surrounding rock reaches between 0.80 and 0.85. Optimization of support parameters: increasing the density of anchors support and enhancing the pre-tension force have a substantial effect on controlling the surrounding rock, whereas extending the length of the anchors does not significantly constrain the displacement of the surrounding rock. Consequently, when implementing anchors support for roadways, it is recommended to adopt a support scheme featuring short anchors, high density, and high preload force, after determining a reasonable support time.

       

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